ABSTRACT
In a sew ag e trea tm en t p lan t, p a rticu la rly fo r large m u n ic ip a litie s , p u m p in g slu d g e fro m o n e lo ca tio n to a n o th e r th ro u g h a p ip e lin e sy s tem is an im p o rtan t op era tio n . T h e d es ig n an d d ay -to -d ay ru n n in g o f su ch a sy s tem is n o t tr iv ia l, b ecau se slu d g e is a Theologically co m p lex flu id w h ich ex h ib its a y ie ld s tress - a m in im u m sh ear s tress n eed ed to s ta rt th e flu id flow ing . T he B in g h am flu id m odel (y ie ld s tress p lu s N e w to n ia n flo w b eh av io r) is th e s im p le s t an d m o s t w id e ly used m o d e l fo r p re d ic tio n o f th e f lo w ch arac te ris tic s (p ressu re d ro p vs. flo w ra te ) o f s lu d g es [1]. H o w ev e r, it is a lso w id e ly k n o w n th a t m o s t s lu d g es do n o t ex h ib it N e w to n ia n b e h a v io r in flow . T h u s , a m o re co m p lex m o d e l, th e y ie ld s tress - p seu d o p la s tic flu id m o d e l (H ersch e l-B u lk ley ), h a s a lso b een p ro p o sed fo r th is p ro b lem [2 ].
